package com.heima.juc.n8;

import com.heima.juc.n2.Sleeper;
import lombok.extern.slf4j.Slf4j;

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.HashSet;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @author : leimingchao
 * @date Date : 2022年02月13日 9:22
 */
@Slf4j(topic = "c.TestPool")
public class TestPool {

    public static void main(String[] args) {
        //1.死等
        // ThreadPool threadPool = new ThreadPool(1, 1000, TimeUnit.MILLISECONDS, 1, BlockingQueue::put);

        //2.带超时等待
        // ThreadPool threadPool = new ThreadPool(1, 1000, TimeUnit.MILLISECONDS, 1, (queue, task) -> {
        //     queue.offer(task, 1500, TimeUnit.MILLISECONDS);
        // });

        //3.让调用者放弃任务执行
        // ThreadPool threadPool = new ThreadPool(1, 1000, TimeUnit.MILLISECONDS, 1, (queue, task) -> {
        //     log.debug("放弃{}",task);
        // });

        //4.让调用者抛出异常
        // ThreadPool threadPool = new ThreadPool(1, 1000, TimeUnit.MILLISECONDS, 1, (queue, task) -> {
        //     throw new RuntimeException("任务执行失败" + task);
        // });

        //5.让调用者自己执行任务
        ThreadPool threadPool = new ThreadPool(1, 1000, TimeUnit.MILLISECONDS, 1, (queue, task) -> {
            task.run();
        });
        for (int i = 0; i < 4; i++) {
            int j = i;
            threadPool.execute(() -> {
                Sleeper.sleep(1);
                log.debug("{}", j);
            });
        }

    }
}

@FunctionalInterface
interface RejectPolicy<T> {

    /**
     *
     * @param queue
     * @param task
     */
    void reject(BlockingQueue<T> queue, T task);
}

@Slf4j(topic = "c.ThreadPool")
class ThreadPool {

    /**
     * 任务队列
     */
    private BlockingQueue<Runnable> taskQueue;

    /**
     * 线程集合
     */
    private HashSet<Worker> workers = new HashSet();

    /**
     * 核心线程数
     */
    private int coreSize;

    /**
     * 获取任务的超时时间
     */
    private long timeout;

    /**
     * 时间单位
     */
    private TimeUnit timeUnit;

    private RejectPolicy<Runnable> rejectPolicy;

    /**
     * 执行任务
     * @param task
     */
    public void execute(Runnable task) {

        synchronized (workers) {
            //当任务数没有超过coreSize时，直接交给worker对象执行
            //如果任务数超过coreSize时，加入任务队列暂存起来
            if (workers.size() < coreSize) {
                Worker worker = new Worker(task);
                log.debug("新增worker：{}，task：{}", worker, task);
                workers.add(worker);
                worker.start();
            } else {
                // taskQueue.put(task);
                //1.死等
                //2.带超时时间等待
                //3.让调用者放弃任务执行
                //4.让调用者抛出异常
                //5.让调用者自己执行任务
                taskQueue.tryPut(rejectPolicy, task);
            }
        }
    }

    public ThreadPool(int coreSize, long timeout, TimeUnit timeUnit, int queueCapacity, RejectPolicy<Runnable> rejectPolicy) {
        this.coreSize = coreSize;
        this.timeout = timeout;
        this.timeUnit = timeUnit;
        this.taskQueue = new BlockingQueue<>(queueCapacity);
        this.rejectPolicy = rejectPolicy;
    }

    class Worker extends Thread {

        private Runnable task;

        public Worker(Runnable task) {
            this.task = task;
        }

        @Override
        public void run() {
            //执行任务
            //1.当task不为空，执行任务
            //2.当task执行完毕，再接着从任务队列中获取任务，并执行
            // while (task != null || (task =taskQueue.take()) != null) {
            while (task != null || (task =taskQueue.poll(timeout, timeUnit)) != null) {
                try {
                    log.debug("正在执行。。。{}", task);
                    task.run();
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    task = null;
                }
            }

            synchronized (workers) {
                log.debug("worker 被移除：{}", this);
                workers.remove(this);
            }
        }
    }
}

@Slf4j(topic = "c.BlockingQueue")
class BlockingQueue<T> {

    /**
     * 1.任务队列
     */
    private Deque<T> queue = new ArrayDeque<>();

    /**
     * 2.锁
     */
    private ReentrantLock lock = new ReentrantLock();

    /**
     * 3.生产者条件变量
     */
    private Condition fullWaitSet = lock.newCondition();

    /**
     * 4.消费者条件变量
     */
    private Condition emptyWaitSet = lock.newCondition();

    /**
     * 5.容量上限
     */
    private int capacity;

    public BlockingQueue(int capacity) {
        this.capacity = capacity;
    }

    /**
     * 带超时的阻塞获取
     * @return
     */
    public T poll(long timeout, TimeUnit timeUnit) {

        lock.lock();
        try {
            //将timeout超时时间统一转换为纳秒
            long nanos = timeUnit.toNanos(timeout);
            while (queue.isEmpty()) {
                try {
                    if (nanos <= 0) {
                        return null;
                    }
                    //返回的是剩余的时间
                    nanos = emptyWaitSet.awaitNanos(nanos);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            T t = queue.removeFirst();
            fullWaitSet.signal();
            return t;

        } finally {
            lock.unlock();
        }
    }

    /**
     * take 阻塞获取
     */
    public T take() {
        lock.lock();
        try {
            while (queue.isEmpty()) {
                try {
                    emptyWaitSet.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            T t = queue.removeFirst();
            fullWaitSet.signal();
            return t;

        } finally {
            lock.unlock();
        }
    }

    /**
     * 阻塞添加
     */
    public void put(T task) {

        lock.lock();

        try {

            while (queue.size() == capacity) {
                try {
                    log.debug("等待加入任务队列：{}", task);
                    fullWaitSet.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            log.debug("加入任务队列：{}", task);
            queue.addLast(task);
            emptyWaitSet.signal();

        } finally {
            lock.unlock();
        }
    }

    /**
     * 待超时时间的添加
     * @param task
     * @param timeout
     * @param timeUnit
     * @return
     */
    public boolean offer(T task, long timeout, TimeUnit timeUnit) {
        lock.lock();

        try {
            long nanos = timeUnit.toNanos(timeout);
            while (queue.size() == capacity) {
                try {
                    log.debug("等待加入任务队列：{}", task);
                    if (nanos <= 0) {
                        return false;
                    }
                    nanos = fullWaitSet.awaitNanos(nanos);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            log.debug("加入任务队列：{}", task);
            queue.addLast(task);
            emptyWaitSet.signal();
            return true;
        } finally {
            lock.unlock();
        }
    }

    /**
     * 获取大小
     * @return
     */
    public int size() {
        lock.lock();

        try {

            return queue.size();
        } finally {
            lock.unlock();
        }
    }

    public void tryPut(RejectPolicy<T> rejectPolicy, T task) {

        lock.lock();
        try {
            //判断队列是否已满
            if (queue.size() == capacity) {
                rejectPolicy.reject(this, task);
            } else {
                log.debug("加入任务队列：{}", task);
                queue.addLast(task);
                emptyWaitSet.signal();
            }
        } finally {
            lock.unlock();
        }
    }
}
